Macular degeneration is a leading cause of blindness in the Western World that affects the aging population. The complexity of the molecular basis of age-related macular degeneration is now beginning to be elucidated with the identification of disease-causing loci through multiple genome scans. This proposal describes a follow-up to two genome scans, one on a community based study (The Beaver Dam Eye Study) and the second in sample obtained from a Retinal Clinic (The Family Age Related Maculopathy Study) conducted by our group. We have evidence of a major locus on chromosome 15q21 (GATA50C03 multipoint P = 1.98 x 10[7]; empirical P < 10[-5]; singlepoint P = 3.6 x 10[-7]) in the Family Age Related Maculopathy Study. This locus was present as a weak linkage signal in our previous ARMD genome scan in the Beaver Dam Eye Study sample (D15S659 multipoint P=0.047), which represents a replication of our results. In the current proposal we will follow up our initial results by fine mapping the region on 15q. We have presented a tiered strategy to perform fine mapping, including validating our results in a sample of cases and controls from the Age-Related Eye Disease Study. We also propose to map other loci that demonstrated positive linkage signals in our genome scan. The cloning of genes for the heritable forms of macular degeneration will increase our understanding of the basic pathogenesis of the disease process. Further, since we propose to examine a case control sample, we will be able to obtain initial estimates of attributable risk due to a particular gene in the population.